This invention relates to the construction of a three-layer metal laminate consisting of two different metals, the two outer, thinner, layers being of the same metal, while the middle layer, which is of a different metal, is thicker, with the result that the laminate acquires a bimetal effect. The invention also concerns the application of this laminate in vessels for preparing and keeping food.
It is known that in vessels for preparing food by means of heat, there arises a temperature gradient in the vessel base which can result in its bulging. This deformation impairs the efficiency of heat transfer from flat hotplates, and furthermore results in local overheating of the vessel with scorching of the contents and other unpleasant consequences.
To avoid these difficulties, several possibilities have been tried. In the case of thin-based saucepans it is necessary, for example, to curve the base inwards to prevent the saucepan from "dancing" on the hotplate.
In the case of saucepans of stainless steel of the 18/8 steel type, or of a laminate of stainless steel, it is necessary, in order to make the utensil satisfactory in use, to apply a comparatively thick extra base, usually of copper or aluminum, in order to improve heat distribution. It is further necessary to have comparatively thick material in the sides and in the base to achieve satisfactory stability. As a result of this, saucepans of stainless steel, or of a stainless steel laminate, are comparatively heavy, and production costs are high.